Problem: Express your answer as a mixed number simplified to lowest terms. $18\dfrac{15}{18}-7\dfrac{13}{18} = {?}$
Answer: Separate the whole numbers from the fractional parts: $= {18} + {\dfrac{15}{18}} - {7} - {\dfrac{13}{18}}$ Bring the whole numbers together and the fractions together: $= {18} - {7} + {\dfrac{15}{18}} - {\dfrac{13}{18}}$ Subtract the whole numbers: $=11 + {\dfrac{15}{18}} - {\dfrac{13}{18}}$ Subtract the fractions: $= 11+\dfrac{2}{18}$ Combine the whole and fractional parts into a mixed number: $= 11\dfrac{2}{18}$